So I have a 1970 Barracuda and my original wiring had the normal "single" ballast and no support for ECU. I ordered the new engine wiring harness from YearOne, I specified electronic ignition and so it came with double-ballast connectors and support for the ECU.

I did not have to do anything extra except buy a double resister and it works excellent!

Also, I took the online wiring images for our car and used some tools to clean them up and glue them together. I think the .PDF files are too big to post so if you PM me your email address I will email the PDF to you. I have a plotter at home and so when I am working on my car I print them poster-sized and it helps me when I am under the hood. I have a few other wiring images I have collected as well that may help. PM me and I will get these all to you.